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Math Help - Please help me on my Homework.

  1. #1
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    Post Please help me on my Homework.

    I need show the following is an identity. (thanks)

    cos(3t)=4cos^3(t)-3cos(t)
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  2. #2
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    Re: Please help me on my Homework.

    Hey TrimHonduras.

    Hint: Try using the sum of angles of formula to get cos(3t) down to cos(2t), cos(t), sin(2t) and sin(t) and then use it again to get sin(2t) in terms of sin(t) and cos(t) and also cos(2t) in terms of sin(t) and cos(t) and then collect everything together.
    Thanks from TrimHonduras and topsquark
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  3. #3
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    Re: Please help me on my Homework.

    Please help me on my Homework.-capture-trig.png
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  4. #4
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    Re: Please help me on my Homework.

    So far I got that but I don't know what to do next.... maybe I got something wrong...
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